Apparatus for applying labels coated with pressure-sensitive adhesive

ABSTRACT

The apparatus serves to stick the labels on articles which move past the apparatus in synchronism therewith, particularly to stick end labels of plastics material sheeting on the folded ends of bags to protect and reinforce said ends. The apparatus comprises feeding means for an intermittent or continuous feeding of a label web, which is unilaterally coated with pressuresensitive adhesive and consists, e.g., of plastics material sheeting. The apparatus also comprises a continuously rotating applying roller, which succeeds said feeding means and is provided with vacuum-applying means at its periphery and cooperates with a cross-cutter in such a manner that the labels are severed from the label web and stuck on the folded ends of the articles, which are tangentially moved past the applying roller in synchronism therewith. Said applying roller revolves at a higher peripheral velocity than the feeding means. The means for feeding the label web consist of a continuously rotating vacuum drum, which is contacted by the label web on its uncoated side, and a flat vacuum-applying member, which extends approximately in the direction of the common tangent to the vacuum drum and applying roller and is covered by at least one driven endless vacuum belt.

United States Patent [191 Brinkmeier [451 Aug. 12, 1975 [75] Inventor: Friedhelm Brinkmeier, Ladbergen,

Germany [73] Assignee: Windmoller & Holscher, Lengerich,

Germany 22 Filed: July 18,1973

21 Appl. No.: 380,198

[30] Foreign Application Priority Data Aug. 8, 1972 Germany 2237846 [52] US. Cl. 156/521; 83/152; 156/567; 156/DIG. 31; 226/95; 271/197; 271/276 [51] Int. Cl. B650 9/14 [58] Field of Search 156/521, 567, 517, DIG. 24,

3,654,038 4/1972 Hottendorf 156/521 FOREIGN PATENTS OR APPLICATIONS 1,367,081 7/1963 France 226/95 Primary ExaminerCharles E. Van Horn Assistant Examiner.l. Gallagher Attorney, Agent, or F irmFleit & Jacobson 5 7 ABSTRACT The apparatus serves to stick the labels on articles which move past the apparatus in synchronism therewith, particularly to stick end labels of plastics material sheeting on the folded ends of bags to protect and reinforce said ends. The apparatus comprises feeding means for an intermittent or continuous feeding of a label web, which is unilaterally coated with pressuresensitive adhesive and consists, e.g., of plastics material sheeting. The apparatus also comprises a continuously rotating applying roller, which succeeds said feeding means and is provided with vacuum-applying means at its periphery and cooperates with a crosscutter in such a manner that the labels are severed from the label web and stuck on the folded ends of the articles, which are tangentially moved past the applying roller in synchronism therewith. Said applying roller revolves at a higher peripheral velocity than the feeding means. The means for feeding the label web consist of a continuously rotating vacuum drum, which is contacted by the label web on its uncoated side, and a flat vacuum-applying member, which extends approximately in the direction of the common tangent to the vacuum drum and applying roller and is covered by at least one driven endless vacuum belt.

5 Claims, 1 Drawing Figure APPARATUS FOR APPLYING LABELS COATED WITH PRESSURE-SENSITIVE ADHESIVE This invention relates to an apparatus for sticking labels coated with pressure-sensitive adhesive on articles which are moved past the apparatus in synchronism therewith, particularly for sticking end labels of plastics material sheeting on the folded ends of bags to protect and reinforce said ends.

The coating of pressure-sensitive adhesive has a very high bonding strength, which is rendered fully effective upon even slight contact. Until the adhesive labels have been cut from the adhesive-coated, coherent web, backing or feed rollers may contact the web on its adhesive side if the web section which succeeds the contacting element in the direction of travel of the web is always subjected to tension so that the contacting element can be pulled from the constantly tensioned, adhesive web. If the web tension is continually interrupted because labels are cut in succession from the web, special measures must be adopted to maintain the tension in the web as far as to a point which is close to the cutting tool, and to provide pulling means which engage the web only on the non-adhesive side. Because "the label must be stuck on the article with a high precision, any contact of the coating of pressure-sensitive adhesive with parts of the sticking apparatus must be avoided because when the web is pulled from contacting parts the adhesion to said parts changes with time so that the pull-off tension to which the web material is subjected is varied. As a result, the material travels at a changing velocity. Measures to reliably prevent a wandering or shifting of the labels must be adopted where such contact is inevitable, e.g., adjacent to the knives used to cut the labels from a label web.

An apparatus for sticking labels coated with pressure-sensitive adhesive is known from the US. Pat. No. 2,990,081 and comprises feeding means for an intermittent or continuous feeding of a label web, with is unilaterally coated with pressure-sensitive adhesive, and a continuously rotating applying roller which succeeds said feeding means and is provided with vacuumapplying means throughout its periphery and cooperates with a cross-cutter in such a manner that the labels are severed from the label web and are stuck on the articles, which are tangentially moved past the applying roller in synchronism therewith, said applying roller revolving at a higher peripheral velocity than the feeding means.

In that known apparatus, the means for feeding the label web comprise a continuously or intermittently rotating feed roller, which is wrapped by the label web so that the pressure-sensitive adhesive coating of said web contacts the periphery of the feed roller. The label web is entrained by the feed roller owing to the bonding strength of the adhesive on the web. The applying roller succeeds the feed roller and applies a vacuum to the uncoated side of the label web so that the latter is held in contact with the periphery of the applying roller but can be shifted thereon in the direction of rotation. To cut the labels from the label web, the applying roller is associated with a cross-cutter, which comprises a guillotine knife and in dependence on the feed increment of the label web, which feed increment is determined by the feed roller, reciprocates said knife toward and from the periphery of the applying roller to sever successive labels in a length which corresponds to the feed increment of the label web from the latter. Because the feed roller has a lower peripheral velocity than the applying roller, the label web cannot move on the applying roller at a velocity which is higher than the velocity imparted to the web by the feed roller. For this reason, the label web slides on the periphery of the applying roller against the action of the frictional forces which are due to the vacuum applied by the applying roller to the web. On the other hand, the label which has been severed from the label web is advanced at the higher peripheral velocity of the applying web and is finally stuck on the article that is moved past the applying roller. The difference between the velocities of the applying roller and the feed roller determines the spacing of the labels as they are stuck on the articles. This spacing is selected to correspond to the pitch of the continuously advanced articles so that each article receives the label stuck thereon exactly at the same location.

In that known apparatus, the operation of the feed roller results in uncontrollable changes in the length of the labels because the bonding strength of the adhesive coating cannot be maintained constant with the required accuracy throughout the length of the adhesive web. The label web will inevitably have portions which stick better than other portions. The pull-off tension which must be applied by the applying roller to pull the adhesive web from the feed roller will vary accordingly. For this reason, the angle of wrap of the label web on the feed roller will vary in the same sense as the bonding strength. A larger angle of wrap will result in a severed label having a smaller length, and a smaller angle of wrap will result in a severed label having a larger length. This action is promoted by the applying roller because the same is provided with vacuum bores around its periphery and it is inherent in the design that the label web does not cover all vacuum bores so that -more or less air is sucked into the vacuum cylinder. The

changes of the rate at which air enters through the open vacuum bores into the vacuum chamber of the applying roller result in considerable changes of the vacuum applied by the applying roller so that the label web is held by a varying force in contact with the periphery of the applying roller.

The vacuum applied by the applying roller may be so small that severed labels are no longer held exactly in position on the periphery of the applying roller as reliably as is required when the adhesive coating adheres to the knife during the cutting operation. This often gives rise to trouble.

It is an object of the invention to eliminate the abovementioned disadvantages of the known apparatus and to teach improvements which prevent uncontrollable changes in the length and position of the label even when the apparatus operates at a high rate.

This object is accomplished according to the invention in that the means for feeding the label web consist of a continuously rotating vacuum drum, which is contacted by the label web on its uncoated side, and a flat vacuum-applying member, which extends approximately in the direction of the common tangent to the vacuum drum and applying roller and is covered by at least one driven endless vacuum belt. Because the vacuum drum is contacted by the label web on the uncoated side of the latter, the web is immovably held in contact with the vacuum drum by a vacuum which acts on the label web only within its angle of wrap. This ensures a feeding of the label web in accurately uniform increments per unit of time, regardless of the bonding strength and any variation of the peeling strength. The flat vacuum-applying member ensures that the label web leaves the vacuum drum always at one and the same point, that the web which has been moved from the drum is held straight for high reliability of operation and that the web is guided toward the periphery of the applying roller in such a manner that a buckling or the like of the web is avoided.

This design of the apparatus according to the invention ensures a constant length and spacing of the labels severed from the label web and avoids any shifting of said labels on the applying drum so that all labels are stuck on the articles with a high accuracy. When label webs are processed which consist of highly pliable materials, which tend to curl and/or to receive electrostatic charges, particularly of plastics material sheeting, the flat vacuum-applying member disposed between the vacuum drum and the applying roller prevents a catching of the web or a rising thereof, e.g., as a result of a tendency to curl, and holds the label web reliably in a flat position as it is transferred to the applying roller. The vacuum belts prevent a retention of the label web on the vacuum drum as a result of adhesive electrostatic forces before the web engages the guideway and thus ensure that the web is not pulled into the inevitable gap between the vacuum drum and the guideway. The endless vacuum belts are suitably trained around and driven by the vacuum drum. This arrangement eliminates the need for separate means for driving the vacuum belts and at the same time provides for a good bridging of the gap between the vacuum drum and the flat sucking member.

To enable a reliable cutting of the label from the web without undesired buckling effects which would give rise to trouble, and to enable a reliable holding of the cut-off label in contact with the applying roller, it is a further feature of the invention to provide the applying roller at its periphery with a knife having a cutting edge disposed in the surface of the roller, and with vacuum openings arranged in at least two axially extending rows, one of which precedes the knife at a small distance therefrom and the other of which precedes the knife at a distance therefrom which corresponds approximately to the desired label length, in the direction of rotation of the applying roller.

According to a further feature of the invention, the leading row of vacuum holes in the applying roller are provided in a vacuum beam, which is adjustable in the peripheral direction of the latter. As a result, the apparatus can quickly be adjusted to labels having a different length. The feeding velocity of the label web is changed in accordance with the selected length of the labels by the use of change gears in the means for driving the vacuum drum.

The leading end of the label web and of the trailing end of a just severed label might be entrained by the retating backing knife cooperating with the knife of the applying roller because adhesive has become deposited on said backing knife. To prevent such entraining, it is a further feature of the invention to rotate the backing knife at a peripheral velocity which exceeds the feeding velocity imparted to the label web by the vacuum drum and which is smaller than the peripheral velocity of the knife carried by the applying roller. As a result, the label web end which adheres to the backing knife during the cutting operation is pulled from the backing knife in the direction of the label web because the backing knife has a higher peripheral velocity, and the label which has just been severed and adheres to the backing knife and is held in contact with the applying roller by the rows of vacuum holes thereof is also pulled from the backing knife in the direction of the label web by the applying roller rotating at a higher peripheral velocity. As a result, the label web and the label adhering to the backing knife cannot be entrained by the latter and the severed label cannot be shifted or turned on the applying roller.

An embodiment of the apparatus according to the invention is shown by way of example on the drawing in an elevation.

The apparatus which is shown serves to stick endcovering labels Z preferably of plastics material sheeting on the folded ends F of bags S which are also made of plastics material sheeting.

The apparatus comprises a vacuum drum 1 for continuously feeding a label web ZB, which is unilaterally coated with pressure-sensitive adhesive. The apparatus also comprises a flat guideway 2, a cross-cutter 3, 4, and a continuously rotating applying roller 5 for sticking the labels, which have been cut from the label web, on the folded ends of the bags which are tangentially moved past the applying roller 5 in synchronism therewith. The vacuum drum 1 and the applying roller 5 are mounted in stationary positions in a machine frame 6. The guideway 2 extends between the vacuum drum and the applying roller along the tangent which is common thereto. The apparatus is driven by means of the shaft 7 of the applying roller 5. The latter revolves in the direction of travel a of the bags at a peripheral velocity which is equal to the velocity at which the bags travel. The vacuum drum 1 is driven in the same direction of rotation a by means of gears 8, 9, and 10. The intermediate gear 9 is mounted in a rocker 12, which is pivoted on the axis 11 of the vacuum drum and can be fixed in position. The rotational movement performed by the vacuum drum per cycle time determines the length of the cut-off label Z. Said gear drive is disposed on the side of the apparatus so that the gear 8 can easily be replaced by a gear having a different number of teeth so that any desired other peripheral velocity of the vacuum drum 1 can be selected in conjunction with a given cycle time to obtain labels having a different length. The peripheral velocity of the vacuum drum 1 is always lower than that of the applying roller 5. The vacuum drum is provided in known manner with radial vacuum bores 13 in its periphery and is provided internally with a stationary vacuum box 14, which ensures that the vacuum action of the vacuum drum is restricted to the region defined by the angle of wrap a between the initial point of contact x with the label web 23 and the point of contact y with the tangent along which the guideway 2 extends.

The guideway 2 consists of a vacuum box 15 which has vacuum slots 16, which are covered by one or more endless perforated vacuum belts 17. The latter are trained around the vacuum drum 1 in guide grooves having a depth that the vacuum belts are flush with the periphery of the drum. The vacuum belts moving away from the vacuum box 15 are guided by guide rollers l8,

19, 20 back to the vacuum drum.

The applying roller 5 has a circumference which corresponds to the pitch 1 of the bags 8 so that the spacing of the locations in which the labels are stuck is determined by the diameter of the applying roller 5. The latter is driven to perform exactly one revolution per cycle. The roller 5 is provided with a knife 3, which extends throughout the length of the roller and which cooperates with the rotating backing knife 4. The latter is driven by the gear 28, mounted on the shaft 7 of the applying roller, and the gear 21, at the same angular velocity as the applying roller 5. The flight circle 40 of the backing knife is dimensioned so that the peripheral velocity of the backing knife is higher than the velocity at which the label web ZB is fed and smaller than the peripheral velocity of the knife 3 which is carried by the applying roller 5. A row of vacuum bores 22 open at the periphery of the applying drum along a line which slightly precedes the knife 3 in the direction of rotation a. Another row of vacuum bores 23 open along a line which precedes the vacuum bores in the direction of rotation a. The vacuum bores 23 are provided in a vacuum box 24, which is adjustable in the peripheral direction of the applying roller, as is indicated by the arrow b. Said vacuum bores communicate with vacuum sources through the axial manifold bores 25, 26 and a stationary valve head, not shown, which is provided on one end of the applying roller and restricts the vacuum action of the vacuum bores approximately to the region defined by the angle B.

A change gear 8 is selected which ensures that the vacuum drum 1 feeds the label web 28 at such a velocity that the increment by which the label web is fed during each revolution of the applying roller is exactly equal to the desired length l of the end labels Z to be stuck. The distance from the row of vacuum bores 23 to the knife 3 of the applying roller is selected to be approximately as large as and only slightly less than the desired length of the label.

At the point x the label web 28 coated on one side with pressure-sensitive adhesive initially contacts with its uncoated side the vacuum drum 1, which applies a vacuum to hold the web in contact with the periphery of the vacuum drum within the range of the angle of wrap a and to advance the web at the peripheral velocity of the vacuum drum. The vacuum belts l7 lift the label web from the vacuum drum at the point y and move it over the vacuum box close to the applying roller 5, which rotates at a peripheral velocity which exceeds the velocity at which the label web is fed by the vacuum drum 1. When the label web has left the lower end of the vacuum box, the uncoated side of the label web loosely contacts the applying roller, which revolves at a higher velocity, and the web is then sucked by the vacuum bores 23 and 22 of the applying roller as soon as these bores reach the web. Because the force by which the label web is held at the vacuum bores 23, 22 is smaller than the force by which the label web is held in the long vacuum zone provided by the vacuum drum 1 and the vacuum belts 17, the applying roller rotates in sliding contact with the label web, which continues to move at the velocity at which it has been fed. The vacuum bores 23 and 22 only hold the end of the label web in contact with the periphery of the applying roller so that the label web is held taut before an end label is cut from the label web, as is shown on the drawing. Because the velocity at which the label web is fed (change gear 8) and the distance from the vacuum bore 23 of the applying roller 5 from the knife 3 are selected as described, the leading end of the label web is still adjacent to the vacuum bores 23. The end label which has been cut off is thus held at its two ends by the vacuum bores 23 and 22 in contact with the periphery of the applying roller in a taut condition and is stuck exactly and without wrinkles on the bag S which moves tangentially past the applying roller 5 in synchronism therewith.

What is claimed is:

1. Apparatus for sticking labels coated with pressuresensitive adhesive on articles which are moved past the apparatus in synchronism therewith, particularly for sticking end labels of plastics material sheeting on the folded ends of bags to protect and reinforce said ends, comprising feeding means for a continuous feeding of a label web, which is unilaterally coated with pressuresensitive adhesive, and a continuously rotating applying roller which succeeds said feeding means and is provided with vacuum-applying means at its periphery and cooperates with a cross-cutter in such a manner that the labels are severed from the label web and are stuck on the folded ends of the articles, which are tangentially moved past the applying roller in synchronism therewith, said applying roller revolving at a higher peripheral velocity than the feeding means, characterized in that the means for feeding the label web comprises a continuously rotating vacuum drum, which is contacted by the label web on its uncoated side, and a flat vacuum-applying member, which extends approximately in the direction of the common tangent to the vacuum drum and applying roller and is covered by at least one driven endless vacuum belt.

2. Apparatus according to claim 1, characterized in that more than one endless vacuum belt is trained around the vacuum drum and driven thereby and are further trained over guiding and tensioning rollers.

3. Apparatus according to claim 1, characterized in that the applying roller is provided at its periphery with a knife having a cutting edge disposed in the surface of the roller, and the vacuum openings arranged in at least two axially extending rows, one of which precedes the knife at a small distance therefrom and the other of which precedes the knife at a distance therefrom which corresponds approximately to the desired label length, in the direction of rotation of the applying roller.

4. Apparatus according to claim 3, characterized in that the leading row of vacuum holes in the applying roller are provided in a vacuum beam which is adjustable in the peripheral direction of the applying roller.

5. Apparatus according to claim 1, which includes a cross-cutter, which comprises two knives, which revolve in mutually opposite senses and meet for the cutting operation, one of said knives being arranged in the applying roller and the other being a backing knife arranged in a knife roller, characterized in the peripheral velocity of said backing knife exceeds the velocity at which the label web is fed by the vacuum drum and is less than the peripheral velocity of the knife carried by the applying roller. 

1. APPARATUS FOR STICKING LABELS COATED WITH PRESSURE-SEMITIVE ADHESIVE ON ARTICLES WHICH ARE MOVED PAST THE APPARATUS IN SYNACHRONISM THEREWITH, PARTICULARLY FOR STICKING END LABELS OF PLASTIC MATERIAL SHEETING ON THE FOLDED ENDS OF BAGS TO PROTECT AND REINFORCE SAID ENDS COMPRISING FEEDING MEANS FOR A CONTINUOUS FEEDING OF A LABEL WEB, WHICH IS UNILATERALLY COATED WITH PRESSURE-SENSITIVE ADHESIVE, AND A CONTINUOUSLY ROTATING APPLYING ROLLER WHICH SUCCEDEES SAID FEEDING MEANS AND IS PROVIDED WITH VACUUM-APPLYING MEANS AT ITS PERIPHERY AND COOPERATES WITH A CROSS-CUTTER IN SUCH A MANNER THAT THE LABLES ARE SEVERED FROM THE LABEL WED AND ARE STUCK ON THE FOLDED ENDS OF THE ARTICLES, WHICH ARE TANGENTIALLY MOVED PAST THE APPLYING ROLLER IN SYNCHRONISM THEREWITH, SAID APPLYING ROLLER REVOLVING AT A HIGHER PRIPHERAL VELOCITY THAN THE FEEDING MEANS, CHARACTERIZED IN THAT THE MEANS FOR FEEDING THE LABEL WEB COMPRISES A CONTINUOUSLY ROTATING VACUUM DRUM, WHICH IS CONTACTED BY THE LABEL WEB ON ITS UNCOATED SIDE, AND A FLAT VACUUM-APPLYING MEMBER, WHICH EXTENDS APPROXIMATELY IN THE DIRECTION OF THE COMMON TANGENT TO THE VACUUM DRUM
 2. Apparatus according to claim 1, characterized in that more than one endless vacuum belt is trained around the vacuum drum and driven thereby and are further trained over guiding and tensioning rollers.
 3. Apparatus according to claim 1, characterized in that the applying roller is provided at its periphery with a knife having a cutting edge disposed in the surface of the roller, and the vacuum openings arranged in at least two axially extending rows, one of which precedes the knife at a small distance therefrom and the other of which precedes the knife at a distance therefrom which corresponds approximately to the desired label length, in the direction of rotation of the applying roller.
 4. Apparatus according to claim 3, characterized in that the leading row of vacuum holes in the applying roller are provided in a vacuum beam which is adjustable in the peripheral direction of the applying roller.
 5. Apparatus according to claim 1, which includes a cross-cutter, which comprises two knives, which revolve in mutually opposite senses and meet for the cutting operation, one of said knives being arranged in the applying roller and the other being a backing knife arranged in a knife roller, characterized in the peripheral velocity of said backing knife exceeds the velocity at which the label web is fed by the vacuum drum and is less than the peripheral velocity of the knife carried by the applying roller. 